Muscle Car Suspension Basics - Turning The Corner

If You Want To Maximize Handling, You Have To Understand The Basics Of Suspension Design And Spend Money Where It Counts Most

You always want to fine tune with the sway bars and shocks. Also, as soon as you put more load into a car with stiffer springs and sway bars, you need to strengthen the chassis with subframe connectors.-Kyle Tucker

Quick NotesWhat We DidIntroduce you to suspension basics.

Bottom LineThe technology is here to transform any muscle car into a corner carver.

Cost (Approx)As little as $43 for shocks and more for complete out-of-the-box packages

The import guys-at least the two that are still left-think that coilover technology descended from the chariots that travel the golden streets of heaven, but coilovers are actually very simple devices. Aftermarket tubular control arms are superior to stock arms in almost every respect, but it has nothing to do with the fact that they're built from tubular steel. Such misconceptions aren't so much the product of misinformation as they are the consequence of not having enough information. Likewise, while it's no secret that stiffer springs, bigger sway bars, and adjustable shocks can dramatically improve a car's handling, very few people truly know why. Understanding the principles of suspension design at the most fundamental level is mandatory in order to improve your car's handling, so we'll take a crack at explaining it all.

Some of the information here may seem very rudimentary, but the extreme nature of suspension dynamics requires starting at square one. For instance, a few millimeters in additional sway bar thickness may seem insignificant, but such a miniscule change in diameter can yield a 50 percent increase in bar stiffness. Likewise, if you want to cut your car's body roll angle in half, but don't think sway bars are worth the money, then you'll have to double your current spring rate.

In addition to explaining the fundamentals, loads of hot-button topics need to be addressed. Is stiffer always better? Are linear rate springs junk? Are you man enough for double-adjustable shocks? Do coilovers deserve the hype? Are four-links just for drag racing? Should you replace your knees with urethane bushings? If you want to turn the corner in your understanding of suspension design, then turn your attention to the next page. To get the down-low on suspension tuning, we enlisted the help of Kyle Tucker of Detroit Speed and Engineering, Tom Brown of Heidt's, Bret Voelkel of Air Ride Technologies, and Chris Alston of Chassisworks.

3/21

As a result of a larger diameter and a shorter swing arm length, the bottom sway bar is substantially stiffer than the unit on top. In practice, this is because the front sway bar (bottom) must endure greater cornering loads than the rear bar (top). However, differences in sway bar design between a matched set of front and rear sway bars clearly illustrates the effects of diameter and swing arm length on overall stiffness.

Sway BarsWhether you call them sway bars, antiroll bars, or stabilizer bars, they are one in the same. By attaching the left and right sides of a car's suspension together and anchoring them both to the frame, sway bars help resist body roll by increasing roll stiffness. In the front suspension, the sway bar anchors the lower control arms to the frame. In the car's posterior, the sway bar usually attaches from the rearend housing to the frame. As a car's body begins to lean upon corner entry, cornering loads twist the sway bar. Consequently, it is the bar's torsional stiffness that determines how much the body roll is reduced.

The three primary factors that determine a sway bar's torsional stiffness are its diameter and swing arm length and whether it is of solid or hollow construction. In regards to sway bar diameter, stiffness can simply be expressed as diameter. For example, take two sway bars that are identical in every respect except for diameter. A 32mm sway bar (324 = 1,048,576) is approximately 70 percent stiffer than a 28mm one (284 = 614,656).

This exponential relationship means that a small increases in diameter substantially increases stiffness, which is important to keep in mind when shopping for a new sway bar.

Although not quite as extreme as tweaking diameter, changes in swing arm length dramatically impact sway bar stiffness as well. The swing arm is the portion of the sway bar that extends from the frame to the control arm or rearend housing. Lengthening the swing arm reduces sway bar stiffness, while shortening it increases stiffness. For example, shortening the swing arm from 10 to 5 inches results in a sway bar that's twice as stiff.

MORE PHOTOS

VIEW FULL GALLERY

xclose

Muscle Car Suspension Basics - Turning The Corner

You always want to fine tune with the sway bars and shocks. Also, as soon as you put more load into a car with stiffer springs and sway bars, you need to strengthen the chassis with subframe connectors.-Kyle Tucker

As a result of a larger diameter and a shorter swing arm length, the bottom sway bar is substantially stiffer than the unit on top. In practice, this is because the front sway bar (bottom) must endure greater cornering loads than the rear bar (top). However, differences in sway bar design between a matched set of front and rear sway bars clearly illustrates the effects of diameter and swing arm length on overall stiffness.

The splined ends on this Chassisworks rear sway bar allows dialing in preload. This eliminates slop between the bar and the endlinks for improved responsiveness.

The spring rate of a coil spring is determined by the wire thickness of the coils, the number of coils, and how tightly the coils are wrapped in a circle (diameter). Linear-rate springs, shown here, have equally spaced coils. On progressive-rate springs, the top coils are closer together than the bottom ones.

As long as your car isn't a fire-breathing 500hp beast that will see lap after lap on a road course, an aftermarket leaf spring suspension system will suffice. This first-gen Camaro DSE kit feature 175-lb/in tapered springs with an antifriction pad wedged between the leaves, which reduces friction and improves ride quality. A matching set of shocks and heavy-duty shackles are also included.

Although air suspension systems trace their roots back to show cars, Air Ride Technologies has proven that air suspensions can more than hold their own on a road course. Air is an excellent springing medium; it gets stiffer the more that it's compressed. Likewise, it can also be set up to behave in a very linear fashion. Unlike traditional coilovers, an air suspension can be adjusted at the touch of a button. These trick Shockwave units feature integrated double-adjustable shocks.

Shocks damp spring motion by converting kinetic energy into thermal energy. Under rigorous use, a shock will begin to fade and lose its damping ability if it can't dissipate heat quickly enough. To combat this effect, DSE has designed an optional remote-mount reservoir canisters that reduce shock fade by increasing fluid capacity.

One of the wildcards when installing a front coilover conversion is the difficulty of mounting them. This Chassisworks setup for fourth-gen F-bodies bolts directly to the stock control arms on the bottom and the factory shock mounts on top by using a supplied adapter. Other vehicles may require bolting or welding new brackets onto the body or frame. Some coilovers can be mounted upside-down, which reduces unsprung weight.

As with the front suspension, rear coilover conversions can sometimes mount to the stock shock mounts, but certain cars require installing new brackets to the rearend housing or frame. This Chassisworks universal coilover kit includes a crossmember for the upper coilover mounts and ears for the rearend housing, and both must be welded in place. The adjustable lower shock mounts allow tweaking ride height without affecting suspension travel or spring rate.

Unlike a suspension optimized for a road course or the street, an autocross setup can take the stiff-spring-and-small-bars approach to achieve proper roll stiffness since it operates on a smooth surface. This arrangement would not respond well to elevation changes on a road course and would ride terribly on the street.

In cars originally equipped with leaf springs, like first- and second-gen Camaros, upgrading to a four-link may or may not be a bolt-in affair. The lower links attach to where the leaf springs used to reside, but the upper links require installing new brackets to the frame. Heidt's four-link kit for first-gen Camaros features a bolt-in upper control arm mount, which is also the rear cradle to which the coilovers attach. While not quite as adjustable as a dedicated drag four-link, the Heidt's design includes a Panhard bar to locate the rearend and offers far more flexibility when subjected to lateral loads to help prevent binding.

Deflection in the bushings can harm suspension geometry and limit the rear suspension's ability to put the power down. Although they transmit the most noise and require regular lubrication, Heim joints virtually eliminate deflection, and they also enable the rearend to articulate from side to side to reduce binding.

Improved strength is just one of the many benefits of an aftermarket control arm. This piece from DSE features an adjustable cross-shaft, which allow the caster angle to be changed by sliding the entire control arm forward or backward. Adjusting caster angle enables fine-tuning the steering feel and straight-line stability.

Many aftermarket front control arms, such as these from Air Ride, position the shock mount lower than stock. That opens up room for a taller shock, which results in greater suspension travel and an improved ride.

Alternatives to deflection-prone rubber bushings and noise-prone Heim joints are urethane and Delrin. While urethane bushings are stiffer than rubber, many experts suggest avoiding them because urethane squeaks, requires regular splashes of grease, and still deflects more than many suspension tuners would like. Delrin, a thermoplastic manufactured by DuPont, is becoming more popular due to its strength and low friction.

DSE's innovative Swivel-Link rear control arm features an outer section that swivels around the inner shaft. Consequently, side-to-side rearend binding is dramatically reduced. The compliance built into the control arms allows the use of softer bushings for reduced road noise.

Although often overlooked, jounce bumpers are cheap insurance. They prevent the lower control arms from hitting the frame when subjected to severe bumps and act as a progressive-rate spring when compressed.

For maximum effectiveness, springs and shocks should be mounted as close to the ball joints as possible, and as close to vertical as packaging constraints allow. Failure to do so yields a large linkage ratio, which reduces the effectiveness of the springs and requires a stiffer rate to compensate. One of the few methods of dialing in more camber gain into the front suspension is with a taller spindle, which raises the location of the upper ball joint.

Tremendous gains in handling are possible with aftermarket control arms, coilovers, and sway bars. Aftermarket front clips go one step further with revised linkage pickup points for optimized suspension geometry. Although Heidt's street rod front clips are based on Mustang II hardware, its new muscle car subframe assemblies are a clean-sheet design. They're available for first- and second-gen Camaros and '68-72 Novas.

It's impossible to know what you suspension's telling you if it's communicating through a sloppy stock steering box. This unit from DSE, which is a direct replacement for the common GM 800 box used from 1964 to 1992, dramatically improves steering feel due to a reduction in internal friction. Furthermore, it is six pounds lighter than stock and features a 12.7:1 steering ratio.